Food Borne Food Borne IllnessIllness
Food Borne IllnessFood Borne Illness Food Borne Illness Can be caused by:Food Borne Illness Can be caused by:
• Food Borne Infections ( Living organisms )Food Borne Infections ( Living organisms )• Food Borne Toxins ( non living chemicals )Food Borne Toxins ( non living chemicals )
Food PoisoningFood Poisoning• Food Borne Toxins ( non living chemicals )Food Borne Toxins ( non living chemicals )• Generated by MicrobesGenerated by Microbes
BacteriaBacteria FungiFungi AlgeaAlgea
• Man made toxinsMan made toxins Agricultural residuesAgricultural residues Antibiotics Antibiotics PreservativesPreservatives
• Naturally occuring toxinsNaturally occuring toxins
Bacterial Food PoisoningBacterial Food Poisoning
Toxins that are destroyed by Toxins that are destroyed by heatingheating Clostridium botulinum Clostridium botulinum
Heat stable toxinsHeat stable toxins Produced by bacteria Produced by bacteria Staphylococcus aureus Staphylococcus aureus Clostridium perfringens Clostridium perfringens Bacillus cereus Bacillus cereus
Food Borne InfectionsFood Borne Infections Causes by Bacteria that must grow in Causes by Bacteria that must grow in
food before eatenfood before eaten• Require large infective dosageRequire large infective dosage
Only BacteriaOnly Bacteria
Caused by Organism that do not have to Caused by Organism that do not have to grow in the food before it is eatengrow in the food before it is eaten• Require small infective dosageRequire small infective dosage
BacteriaBacteria VirusesViruses ParasitesParasites
Staphylococcus aureusStaphylococcus aureusStaphylococcal InfectionsStaphylococcal Infections
• Gram-positive cocci in irregular clustersGram-positive cocci in irregular clusters• Coagulase negative strains make up to 90% of Coagulase negative strains make up to 90% of
skin microbiota (skin microbiota (S. epidermidisS. epidermidis). Only pathogenic ). Only pathogenic when skin is broken or through invasive entry.when skin is broken or through invasive entry.
• Coagulase positive strains tend to be pathogenicCoagulase positive strains tend to be pathogenic. . Almost all pathogenic Almost all pathogenic S. aureusS. aureus strains make strains make coagulase. High correlation between ability to coagulase. High correlation between ability to produce coagulase and production of damaging produce coagulase and production of damaging toxinstoxins::
LeukocidinLeukocidin: Destroys phagocytic white blood cells.: Destroys phagocytic white blood cells. Exfoliative toxinExfoliative toxin: Responsible for scalded skin : Responsible for scalded skin
syndrome.syndrome. EnterotoxinsEnterotoxins: Affect gastrointestinal tract.: Affect gastrointestinal tract.
• S. aureusS. aureus is commonly found in nasal passages. is commonly found in nasal passages.
Staphylococcal Food PoisoningStaphylococcal Food PoisoningCharacteristics:Characteristics: Acute onset of cramps, vomiting, Acute onset of cramps, vomiting,
nausea, occasional diarrhea, low body nausea, occasional diarrhea, low body temperature and blood pressure. temperature and blood pressure.
Recovery is usually complete within 24 Recovery is usually complete within 24 hours. hours.
Mortality is low in healthy individuals, Mortality is low in healthy individuals, higher among immunosuppressed higher among immunosuppressed individuals.individuals.
PathogensPathogens: : S. aureus S. aureus strainstrain that produces that produces an enterotoxin.an enterotoxin.
ReservoirReservoir: Human skin, nasal secretions, : Human skin, nasal secretions, and cow milk. and cow milk.
•On Manitol salt agar
Heamolysis on HBA
Staph Poisoning in USA 2000Staph Poisoning in USA 2000 Principal symptomsPrincipal symptoms
• Nausea, vomiting, retching, abdominal Nausea, vomiting, retching, abdominal cramps, prostrationcramps, prostration
Potential food contamination Potential food contamination
• Meat and meat products, poultry, eggMeat and meat products, poultry, egg• salads (chicken, potato, macaroni),salads (chicken, potato, macaroni),• cream-filled bakery products, milk and cream-filled bakery products, milk and
dairy productsdairy products No. of illnesses No. of illnesses
• 185,060185,060 No. of deaths No. of deaths
• 22
Micro & Macroscopic C. perfringens
NOTE: Large rectangular gram-positive bacilli
Inner beta-hemolysis = θ toxin Outer alpha-hemolysis = α toxin
NOTE: Double zone of hemolysis
Clostridial Cellulitis
Exotoxins Associated with C. perfringens Types A-E
Major
Perfringens Poisoning in USA Perfringens Poisoning in USA 20002000
Principal symptomsPrincipal symptoms Intense abdominal cramps, Intense abdominal cramps,
diarrheadiarrhea Potential food contaminationPotential food contamination
Meat, meat products, graviesMeat, meat products, gravies No. of illnessesNo. of illnesses
248,520248,520 No. of deathsNo. of deaths
77
Clostridium perfringens
Two syndromes – diarrhoea and ‘pig-bel’ (necrotizing enteritis)
The organism – large, non-motile G+ve, anaerobic rod - bacillus
2 forms – vegetative and spore-forming
Strains – Type A (diarrhoea)
- Type C (‘pig-bel’)
Clostridium botulinumClostridium botulinum
Principal symptomsPrincipal symptoms • Weariness, weakness, vertigo, double Weariness, weakness, vertigo, double
vision, difficulty swallowing and vision, difficulty swallowing and speakingspeaking
Potential food contaminationPotential food contamination Improperly canned or fermented goodsImproperly canned or fermented goods
No. of illnessesNo. of illnesses 5858
No. of deathsNo. of deaths 44
Clostridium botulinum
Botulism & infant botulism
(& wound botulism)
The organism – anaerobic, G+ve, spore-forming rod
Clostridium botulinum
Group I – type A, B & F – food spoilage
Group II – type B, E & F
Types A, B, E & F – human botulism
Types C & D – botulism in animals
Clostridium botulinum
Characteristics
- grows anaerobically - spores & toxin resist freezing - spores resist desiccation
Clostridium botulinum
Pathogenesis - neurotoxin inhibits acetylcholine release - ultimately affects peripheral NS
Clostridium botulinum
Botulinum toxin
inhibits acetylcholine
release at
neuromuscular junction
Clostridium botulinum
The illness, continued
- infective dose – few nanograms - all individuals susceptible; infants
<1yr - Rx – toxin removal, supportive Rx
Clostridium botulinum
Sources - human – no
- animal – can be affected
- food – Type E in seafood, Type A in vegetables, honey
- environment – Types A, B & F in soils/sediments Type E – marine
Dust (vacuum cleaner)
Clostridium botulinum
Outbreaks/sporadic casesVery rare in NZ – one case in 1984
– puha & mussels (incomplete lactic acid
fermentation)
Overseas: - roasted egg plant in oil, chopped garlic in oil,
salted fish, tinned salmon, yoghurt, cheese & cheese sauce
Bacillus cereusBacillus cereus
Principal symptomsPrincipal symptoms • Diarrheal—watery diarrhea, abdominal Diarrheal—watery diarrhea, abdominal
cramps and paincramps and pain• Emetic—nausea and vomitingEmetic—nausea and vomiting
Potential food contaminationPotential food contamination
• Meats, milk, vegetables, fish 0Meats, milk, vegetables, fish 0 No. of illnessesNo. of illnesses
• 27,36027,360 No. of deathsNo. of deaths
• 00
Bacillus cereus
Two syndromes – diarrhoeal & emetic
The organism – G+ve spore-forming rod
Toxins – diarrhoeal & emetic
Bacillus cereus
Characteristics
- rapid growth in food at 30-400C
- vegetative cells killed by heat - spores resistant, emetic toxins resistant to heat
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